The major problems that affect the oral cavity are caused by organisms that live in biofilms colonizing the hard and soft tissues. While much has been learned about mature Dental plaque, little is known about the sequence of changes in microbial species that occurs during supra or subgingival plaque development. Even less is know about the soft tissue microbiota and the interplay between soft tissue microbiota and hard tissue microbiota during biofilm development. Two important bulk fluids, saliva and GCF, bathe the biofilm surfaces and play and undetermined role in biofilm development. Thus, the objectives of this application are to define the changes in microbial species that occur during early biofilm re-development and to evaluate factors that might influence this development including diminished salivary flow, lack of natural dentition and changes in gingival inflammatory status. SAl will compare the changes in microbial composition of developing biofilms on hard and soft tissues in 60 periodontally healthy, 60 periodontitis, and 60 denture-wearing, edentulous subjects from initial Dental cleaning to 7 days. Supra and subgingival plaque samples will be taken separately from the mesial aspect of each tooth at baseline and supragingival samples from dentures. Saliva and samples from eight oral soft tissue surfaces will also be collected. Samples will be evaluated individually for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. After initial monitoring, all dentate subjects in each group will receive a Dental cleaning while dentures will be cleaned and disinfected. Thirty randomly selected subjects in each group will receive full mouth "soft tissue cleaning and disinfection. Subjects will refrain from oral hygiene for 7 days during which time Supra and subgingival plaque samples will be taken from randomly selected quadrants at 1, 2, 4, and 7 days. Denture plaque samples will be taken at the same points as saliva and soft tissue samples.SA2 will compare the microbial composition of supra and subgingival plaque, oral soft tissues, and saliva in 60 Sjgren's subjects and 60 matched controls. Full-mouth caries and periodontal status will be assessed and samples of supra and subgingival plaque will be taken from the mesial aspect of each tooth at baseline. In addition, eight soft tissue samples and a saliva sample will be taken. All samples will be evaluated microbiologically as described above. All subjects will receive full mouth SAP and will be re-assessed microbiologically at 28 days. The proposed study should indicate the nature of the microbial changes that occur during biofilm development on hard and soft tissues and the influence that saliva, GCF and the natural dentition have on the developing biofilms.